powerpc/64e: remove PACA_IRQ_EE_EDGE

This is not used anywhere.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200915114650.3980244-3-npiggin@gmail.com